Dielectric compositions



. tween electrodes.

polar elements.

Patented Apr. 21,- 1953 DIELECTRIC COMPOSITIONS Lester A. Brooks, East Norwalk, Conn., Moushy Markarian, North Adams, and Mathew Nazzewski, Adams, Mass., assgnors to Sprague Electric Company, North Adams, Mass., a corporation of Massachusetts Application September 14, 1950, Serial No. 184,838

Claims. 1

This invention relates to improved dielectric compositions Iand more particularly refers to resinous vinyl polymers containing oxygen `and/or sulfur.

The use of vinyl polymers as dielectric materials is well known. Polystyrene, polyvinyl chloride, polyethylene and many other polyvinyl resins are widely used for insulation purposes, e. g. vcable coating, terminals, coil forms, ca'sings 'and the like. In some case-s, the monomeric compounds have been introduced in wound electrical condensers and subsequently polymerized in situ to lproduce la solid dielectric medium be- This procedure is desirable since no 'special containers or sealing devices are required for the unit as with liquid dielectrics. Unfortunately, however, most of the polymers of the vinyl compounds heretofore proposed as dielectric impregnants possess low dielectric constants, which will not permit production of units of the same capacity la's identical condensers impregnated with castor oil, chlorinated diphenyls l and other higher dielectric constant materials.

Thus, there is a need for polymeriza'ble vinyl compounds possessing, in polymer form, a relatively high dielectric constant, low electrical losses, yas well .as a high softening point and a satisfactory resistance to moisture and corrosive atmospheres. This application is a continuation-in-part of our copending patent application Serial Number 559,460, filed October 19, 1944, now Patent No. 2,522,501.

It is an object of this invention to overcome the foregoing disadvantages. It is a further object to produce new and improved dielectric compositions. A stillfurther object i-s to produce stable resinous dielectric materials containing A still further object is to produce new copolymers. Additional objects will become apparent from the following description and claims.

These objects are attained in Iaccordance with the invention wherein vinyl compounds oontain- Acerned with electrical condensers employing the dielectric compositions of the invention. The

i invention is also concerned with methods of pro- 2 l ducing the monomeric vinyl compounds disclosed herein. The polar elements disclosed as components of the monomeric vinyl compounds disclosed herein are oxygen land sulfur although it is contemplated that other polar elements may be similarly employed.

According to one of the preferred embodiments of the invention, new and improved dielectric compositions are produced by polymerizing vinyl compounds containing sulfur so positioned in the monomeric molecule as to be electrically and chemically stable. Thus the polymers may possess the advantages of a polar compound without being subjectto the instability and high electrical losses usually associated therewith.

The compounds in which oxygen is part of a heterocyclic ring and in which the vinyl group is substituted on a carbon in the same or in a different ring may also 'be employed with success. Among these are the following compounds:`

3viny1 diazo oxide 5-vinyl diazo oxide 2-vinyl pyrane 6-vinyl coumarone 'l-vinyl coumarone 2-vinyl cumarane 3-viny1 pyrane 4-vinyl pyrane l-vinyl 'y pyrane 2-vinyl 'y pyrane 3-vinyl 'y pyrane 4-vinyl y pyrane 5-vinyl y pyrane a vinyl furan vinyl furan 2-vinyl coumarone 3-vinyl coum'arone 4-vinyl coumarone 5vinyl coumarone 3vinyl cumarane 4-vinyl cumarane 5-viny1 cumarane 6vinyl cumarane 7-vinyl cumarane l-vinyl brazan-e 2-vinyl brazane B-vinyl brazane 4-vinyl brazane 5-vinyl brazane 6vinyl brazane Z-vinyl brazane 8-viny1 brazane the vinyl group preferably appears on an 'aromatic ring) o-Vinyl diphenyl sulfide m-Vinyl diphenyl sulfide p-Vinyl diphenyl sulfide o-Vinyl phenyl-a-naphthyl sulfide m-Vinyl phenyl-a-naphthyl sulfide p-Vinyl phenyl-a-naphthyl sulfide -vinyl-a-abinaphthyl sulfide o-Vinyl phenyl alkyl suliides m-Vinyl phenyl alkyl sulfides -p-Vinyl phenyl alkyl sulildes` sults.

4vinyl benzothiophene 5vinyl thionaphthene vinyl benzothiophene 6-vinyl thionaphthene l-vinyl thion'aphthene l-vinyl thiopyraneV 2vinyl thionaphthene 2-vinyl thiopyrane 3-vinyl thionaphthene 3-vinyl thiopyrane 4-vinyl thonaphthene In addition 'to the heretofore mentioned sulfur and oxygen containing compounds, heterocyclic vinyl compounds in which two or morepolar elements appear as ring members may be employed in .accordance with `theinvention with goodre- Among these are:

Z-vinylpiazthiole .3-vinyl piazthiole N -vinyl benzoazole 2-vinyl benzoazole 3 -vinylA benzo azole 4Vinyl .benzo'azole l-vinyldiazo oxide 2-vinyl diazo oxide `3vinyl diazo oxide With reference to the compounds heretofore mentioned, it 'is to be understood that various alkylated and/or halogen'ated derivatives of the compounds may be employed to vobtain Iproducts possessing different melting points, dielectric constants, `polymerization properties and the like. Further, isomers of the above mentioned compounds may be employed.

According to Ianother preferred embodiment of the invention, the monomeric vinyl compounds of the invention may be copolymerized jvvith other monomeric ipolymerizable vinyl compounds, to obtain modified vpolymers possessing valuable properties. Among the polymerizabl'e vinyl compounds vvhich 'may be used are styrene and its halogen'ated and/or alkyl'ated derivatives; vinyl acetylenes; ethylene and halogenated -derivatives thereof, such as tetrafluoroethylene; butadiene, etc. `Small percentages of the monomeric 'compounds ofthe invention added tomany of the monomeric compounds listed above, will `.produce, upon polymerization, polymers of increased resilienceand resistance to heat. Y

TABLE .Parlslys Weg t lParts'other i 'p-vinyl Getal t A earance at25 C. Diphenyl monomer YS pp sulfide 100 None None Hard, glassy. 100 do .1% benzoyl per- Hard, glassy, yellowl Y oxide (BP). ish.

75; 25-styrene 'N Hard, glassy. V75'styrene Do. Z5 l25 N-vinyl Reddish, brittle.

g l .carbazo'lev5 .1 95"styrene None Slightly yellowish hard polymer. 95 5 p-dlvmyl do Iniusible polymer.

benzene.

The following examples illustrate suitable methods of ,preparing the compounds folf the invention, but it is to be understood 'that the invention is not limited to the specic processes Vand methodsdescribed.

Example I .-Vinyl diphenyl sulfide Diphenyl sulfide is reacted with acetyl chloride -in the .presence of aluminum chloride. The

ketone thus produced had Aa .boilingpoint of 170 C. at l mm. pressure. The 'ketone was .reduced Iby standard means to the carbinol. The boiling point of the carbinol could not .be determined, as it readily dehydrated by f-itself when heated. The

dehydrated product, para -vinyl biphenyl sul-fide;

had a boiling point of 135-l`40 C. at 1 mm.

pressure.

, EmamplefH vas indicated in the'tablen'belovv.A 4The polymerizations were conducted Afor `24hburs vat l120 C;

The vinyl biphenyl sulfide can 'be copolymerized with butadiene-1,3 to produce rubbery compounds useful as a replacement for natural rubber.

.Other means may be employed for producingy .chlorine or bromine to form a bromo or `chloro ethyl side chain which may be dehydrohalogen- .ated to the vinyl group. Other conventional syntheses Vfor the preparation of vinyl groups on trical purposes, the polymerization is preferably elected by subjecting the monomer to temperatures .from about '70 C. Ato about 150 C. and preferably from `about C. to about l30 C., overextended periods of time. The polymerization may also be effected by use yof benzoyl vperoxide, oxygen, sulfur dioxide, boron triuoride and other Aaccelerating agents commonly employed in the thermoplastic eld.

'The appended drawing illustrates one of the preferred vembodiments of the invention, e. g. an electrical condenser employing one of the compositions ef .the invention as dielectric media. More specifically, I and 2 represent electrode foils, which are convolutely wound and separated by dielectric `material 3 Vand Il. Terminal tabs 0 rand 'l respectively are .connected to :electrode foils I and -2 respectively. Casing or container 5 eicloses all or part -of 'fthe wound condenser um Electrode foils il and 2 may be of aluminum, lead, tin, copper or other highly conducting metal or falloy. Terminal tabs ll and l are similarly selected and are generally of greaterthickness to 'lends'ome degree vof physical rigidity thereto. Dielectric Ispacers 4 and '3 may comprise a porous dielectric material such as a calendereol kraft 'or vlinen paper, the pores of which are substantially completely lled with one of 'the polymers or copolymers of the invention. Alternately, 3 and 4 may represent one or more films of polymer A(formed byextrusion, casting andthe like) in which case a dielectric spacer of paper Wouldxnot berequired. In the case where a porous spacer is employed, it is highly advantageous to impregnate the Wound condenser with one or .more Aof the monomeric compounds disclosed herein, and subsequently cause polymerization thereof byexposure toqeleva'ted temperatures, 'thus polymerizin'g 'the impregnant in situ to vforma compact, durable, vmoisture resistant element. 'Casing 5 may be of metal, of a non-conducting material, such as heavy cardboard, cellulose acetate, kraft paper, etc. It is not necessary to hermetically seal the condenser element, since the resinous dielectric material resists corrosion and moisture.

It is obvious that other forms of condensers such as stacked, rolled and pressed, etc. may be enhanced by use of the dielectric compositions of the invention therein.

The polymers and copolymers heretofore mentioned may be used for a variety of purposes. While they are particularly suitable for use in electrical condenser, ceramic coated wires, and other electrical equipment, they are useful in other fields, such as in the molding of various articles, for example, toilet articles, chinaware, toothbrush handles, furniture, as a wood and/or metal substitute, hardware, etc.; in the production of paints, lacquers, enamels, varnishes, etc.; in lighting fixtures, ultraviolet transmitting Windows, edge-lighting signs, etc.; in the formation by extrusion of filaments and bers for textiles, bristles, window screening, etc.; in the molding of buttons, buckles, etc.; for use on textiles where heat, crease and moisture resistance is desired; as a binder for plywood, cardboard paper, etc.; as a material for film and sheet formation, for use in wrapping foods and sealing containers, etc.

Another embodiment of this invention concerns the use as dielectric materials of mixtures of the polymers of this invention with chlornated biphenyls, chlorinated naphthalenes and `other dielectric compounds which are not true polymers.

In particular, the products hereof are useful in the electrical field as dielectric and molding compounds by virtue of their fairly low power factor, high leakage resistance and breakdown strength, high dielectric constant, etc.

More specific uses in the electrical field are, for example, coil forms, stand-off insulators, insulating rods and bushings, coil mounting strips, insulating beads for coaxial cable and similar applications. Used as an ingredient in special preparation, these products are useful for coating and treating coils and circuit parts for moisture resistance. These products when hydrogenated or otherwise saturated to prevent further polymerization have applications as a cable oil or condenser dielectric, cable impregnant or wire saturant.

In cases where the polymers are used for nondielectric purposes it is generally advisable to incorporate therewith plasticizers and other materials, i. e., various fillers such as Wood, flour, ground mica, rubber, talc, asbestos. zinc oxide, titanium dioxide, quartz, and the like and/or organic or inorganic color pigments. particularly useful When molded articles are made, since they increase the body or quantity These are with only slight increase in cost. Further, some fillers, particularly ground mica, possess high dielectric constants and properties in themselves, and are therefore of considerable value in the manufacture of dielectric compositions generally.

Some uses of the polymers of this invention may require somewhat softer or more flexible properties than are inherent in the polymer itself. It is therefore helpful to add thereto plasticizers or mixtures thereof such as ethylacetanilide, camphor, carbon tetrachloride, ethylene dichloride, hexachlorethane, sodium tric-hloracetate, ethylene dichloride, hexachlorethane, sodium trichloracetate, diphenyl phthalate, dibutyl phthalate, triphenyl phosphate, tricresyl phosphate, chlorinated biphenyls (Arochlors), keto aromatic acids, such as methyl benzolbenzoate, phthalides; substituted phthalides, glycerol, dibenzyl ether, butyl stearate, dixylylethane, paraffin, tritolyl, cresol, diphenylpropane, etc.`

Another embodiment of this invention concerns methods of stopping the polymerization reaction and/or controlling the physical and/or chemical characteristics of the polymer. It is contemplated that the polymerization reaction may be stopped by hydrogenation; then the resulting polymer may be halogenated, etc., if desred, to obtain specific properties of the polymer. It may also be desired to nitrate or sulphonate following the hydrogenation to impart special properties to the polymer.

As many apparently Widely different embodiments of this invention may be made without departing from the spirit and scope hereof, it is to be understood that the invention is not limited to the specific embodiments hereof except as defined in the appended claims.

What is claimed is:

1. A compound selected from the class which conforms to the formula R-S-R-CII=CH2 wherein R and R are aromatic hydrocarbon nuclei in which any unsaturation is of the benzenoid type.

2. A monovinyl biphenyl sulfide in which the vinyl group is the sole substituent.

3. P-vinyl biphenyl sulfide.

4. A polymer of p-vinyl biphenyl sulfide.

5. A resinous composition comprising a polymer of the compound of claim 1.

LESTER A. BROOKS. MOUSHY MARKARIAN. MATHEW NAZZEWSKI.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,043,941 Williams June 9, 1936 2,125,649 Reppe Aug. 2, 1938 

1. A COMPOUND SELECTED FROM THE CLASS WHICH CONFORMS TO THE FORMULA 